Markers for melanoma

Abstract

A method of diagnosing melanoma and/or monitoring melanoma progression, in particular for determining whether the melanoma is likely to have metastatic capabilities, in a subject includes the steps of in a test sample determining the methylation status of FABP5 wherein methylation of the gene indicates a positive diagnosis of melanoma and/or increased methylation of the gene indicates the progression of melanoma. Methods of monitoring melanoma progression may also incorporate measuring the expression levels of FABP5, with low levels of expression indicating a positive diagnosis of melanoma and/or lower levels of expression being indicative of progression of melanoma. Methods of treating melanoma in a subject comprise administering a therapeutically effective amount of a DNA methyltransferase inhibitor or a histone deacetylase inhibitor to the subject such that expression of FABP5 is increased. Microarrays for use in these diagnostic methods and compound screening methods based around monitoring methylation and/or expression of FABP5 are also envisaged.

1 . A method of diagnosing melanoma and/or for monitoring melanoma progression, in particular for determining whether the melanoma is likely to have metastatic capabilities, in a subject comprising, in a test sample, determining the methylation status of FABP5 wherein methylation of the gene indicates a positive diagnosis of melanoma and/or increased methylation of the gene indicates the progression of melanoma. 
     
     
         2 . A method according to  claim 1  wherein the test sample is a sample taken from tissue which is suspected of being a melanoma. 
     
     
         3 . The method according to  claim 1  wherein the methylation status of at least TSPY1 is also determined. 
     
     
         4 . The method according to  claim 1  wherein the methylation status of at least CYBA and/or MT2A is also determined. 
     
     
         5 . The method according to  claim 1  which utilises methylation specific PCR. 
     
     
         6 . The method according to  claim 5  which utilises real-time quantitative methylation specific PCR. 
     
     
         7 . A method of diagnosing melanoma and/or for monitoring melanoma progression, in particular for determining whether the melanoma is likely to have metastatic capabilities, in a subject comprising, in a test sample, determining expression levels of FABP5, wherein a low level of expression indicates a positive diagnosis of melanoma and wherein a statistically significant decrease in the level of expression of FABP5 indicates the progression of melanoma in the subject. 
     
     
         8 . The method according to  claim 7  wherein the expression of at least TSPY1 is also determined. 
     
     
         9 . The method according to  claim 7  wherein the expression of at least CYBA and/or MT2A is also determined. 
     
     
         10 . The method according to  claim 7  wherein gene expression is determined using RT-PCR, preferably quantitative RT-PCR. 
     
     
         11 . The method according to  claim 1  which is used to determine whether the melanoma is in early radial growth phase or a subsequent vertical growth phase. 
     
     
         12 . The method according to  claim 1  which is used to determine the appropriate treatment for the subject. 
     
     
         13 . The method according to  claim 1  wherein the methylation status or level of expression is assessed with reference to a control sample. 
     
     
         14 . The method according to  claim 13  wherein the control sample is taken from normal melanocytes in the subject. 
     
     
         15 . The method according to  claim 13  wherein the control sample is taken from the same tissue as the test sample at an earlier time point. 
     
     
         16 . A method of treating melanoma in a subject comprising administering a therapeutically effective amount of a DNA methyltransferase inhibitor or a histone deacetylase inhibitor to the subject such that expression of FABP5 is increased. 
     
     
         17 . The method according to  claim 16  wherein the level of gene expression is increased to the levels of gene expression found in normal melanocytes. 
     
     
         18 . Use of a DNA methyltransferase inhibitor or a histone deacetylase inhibitor in the manufacture of a medicament for the treatment of melanoma by increasing expression of FABP5. 
     
     
         19 . The use according to  claim 18  wherein the level of gene expression is increased to the levels of gene expression found in normal melanocytes. 
     
     
         20 . A microarray for use in a method of diagnosing melanoma and/or for monitoring melanoma progression, in particular for determining whether the melanoma is likely to have metastatic capabilities, in a subject comprising, in a test sample, determining expression levels of FABP5, wherein a low level of expression indicates a positive diagnosis of melanoma and wherein a statistically significant decrease in the level of expression of FABP5 indicates the progression of melanoma in the subject, comprising probes immobilised on a solid support hybridizing with transcripts or parts thereof of FABP5. 
     
     
         21 . The microarray of  claim 20  which further comprises probes representing transcripts of TSPY1. 
     
     
         22 . The microarray of  claim 20  which further comprises probes representing transcripts of CYBA and/or MT2A. 
     
     
         23 . A microarray for use in the method of claim  1  comprising probes immobilised on a solid support hybridizing with either methylated only or both unmethylated and methylated versions of FABP5 following bisulphite treatment. 
     
     
         24 . The microarray of  claim 23  which further comprises probes hybridizing with either methylated only or both unmethylated and methylated versions of TSPY1. 
     
     
         25 . The microarray of  claim 20  which further comprises probes hybridizing with either methylated only or both unmethylated and methylated versions of CYBA and/or MT2A. 
     
     
         26 . A method of identifying a compound capable of treating or reducing the effects or progression of melanoma comprising the steps of;
 (a) administering the compound to an experimental non-human animal having a melanoma;   (b) generating an expression profile of FABP5;   (c) comparing the expression profile obtained in (b) with the expression profile of the corresponding gene, expressed in a control melanocyte sample which is not a melanoma;   wherein a positive correlation of the expression profiles is indicative that the compound is capable of reducing the effects or progression of melanoma or preventing melanoma.   
     
     
         27 . An in vitro method of identifying a compound capable of treating or reducing the effects or progression of melanoma comprising the steps of;
 (a) administering the compound to a melanoma sample;   (b) generating an expression profile of FABP5;   (c) comparing the expression profile obtained in (b) with the expression profile of the corresponding FABP5 gene, expressed in a control melanocyte sample which is not a melanoma;   wherein a positive correlation of the expression profiles is indicative that the compound is capable of reducing, controlling the progression of, or preventing melanoma.   
     
     
         28 . The method of  claim 26  wherein the control sample is taken from an experimental non-human animal which does not have a melanoma. 
     
     
         29 . The method of  claim 26  wherein the control sample is taken from normal melanocytes in the same non-human animal.